A patient has contracted the disease, which can be spread person to person.

Following recent abnormal water test results, administrators at Mount Sinai Beth Israel Hospital say they're now taking every precaution and working closely with the Department of Health to ensure no one else is exposed to Legionnaires'.

It was an alarming discovery among some of New York City's most vulnerable, when routine water tests at the hospital last month revealed Legionella bacteria growing in several parts of the hospital.

A spokesperson confirms one patient was diagnosed with Legionnaires' and the hospital immediately reached out to the Department of Health for help removing the bacteria and ensuring no further exposure.

As a precaution water restrictions were recommended while the hospital remains fully operational.

Dr. Peter Wenger with St. Peter's University Hospital in New Brunswick says finding this sort of bacteria isn't that unusual.

"It's probably not that completely uncommon so it may be found, but it may not cause disease, it has to be aerosolized," Dr. Wenger said.

Meanwhile, the patient diagnosed with Legionnaires' has been receiving antibiotics and according to doctors is improving.

It's important to stress the hospital is still open and according to health officials it is safe for patients and visitors.